1. Technical Field
The present invention relates to a control method of and a control device for controlling a liquid ejection head, and a liquid ejecting apparatus and is particularly useful for application in discharging a liquid of which the viscosity changes over a wide range.
2. Related Art
An ink jet recording head which discharges a droplet of ink from its nozzle orifice, for example, using pressure by displacement of a piezoelectric actuator, is known as a typical example of a liquid ejection head discharging liquid through its nozzle orifice, which is installed in a liquid ejecting apparatus. In general, this kind of ink jet recording head has a configuration in which a piezoelectric actuator is provided on one side of a flow channel formation substrate on which a pressure generation room communicating with the nozzle orifice is formed, and the droplet of ink is discharged from the nozzle orifice by applying pressure to ink in the pressure generation room by changing the form of this piezoelectric actuator.
Among the ink jet recording devices equipped with the ink jet recording head, there is one which uses ink whose fixing is facilitated by heat. A heater for drying and fixing ink is built into the ink jet recording head of this kind of ink jet recording device. In this case, the temperature of the ink within the ink jet recording head changes over a wide range from low to high, due to the influence of the heater. Therefore, the viscosity of the ink also changes over a wide range. At this point, discharge characteristics of the ink vary greatly with the influence of the viscosity. Therefore, when discharging the ink whose viscosity varies over a wide range with a drive signal with one kind of fixed waveform, there is a problem in that the imbalance between the weight of discharged ink and the speed of the ink causes deterioration in the discharge characteristics.
A drive waveform is disclosed in JP-A-2004-322318, in which a prior pulse section is provided preceding a discharging pulse section with which a droplet of ink is discharged from the nozzle orifice and a vibration control pulse section is provided following the discharging pulse section.
In JP-A-2004-322318, a configuration is disclosed in which the vibration generated to the ink with the prior pulse section is used and the droplet of ink is discharged, with being synchronized with that vibration, in order to reduce the voltage level of the drive signal and suppress dispersion of the discharge of the droplets of ink.
However, in JP-A-2004-322318, the relationship between the viscosity of ink and the drive waveform is not disclosed and there is also a problem in that in a case of high viscosity ink, vibration of a pressure generation room and vibration of meniscus cannot be completely synchronized. That is, the accuracy cannot be secured in the discharge characteristic according to the viscosity changing over a wide range.
This problem occurs not only in the ink jet recording head, but also in a liquid ejection head ejecting liquid other than ink.